My wife recently start using the crockpot to cook legs of lamb. I think she browns the leg first, rubs on a bit of salt and pepper, insets slivers of garlic into the flesh and tosses in a sprig of rosemary. The trick is to put an inverted butter plate in the crockpot and sit the leg on that. Of course, collect all the juices and use the dress the sliced lamb and veggies. No need to thicken.
Only problem I have with this is I do the dishes and the crockpot can be a pain to clean